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Alejandro Celaya:
Creating a content-based Error Handler for Zend Expressive
Jul 29, 2016 @ 09:26:38

In a post to his site Alejandro Celaya shares a method he worked up for creating a content-based error handler in Zend Expressive - a method of changing the error output based on the content it was passed and the Accept header provided.

In one of my tests of the REST API I saw that when an error occurs (404, 405 or 500), I was getting an HTML response, which is not easy to handle when the client is expecting JSON.

I started to dig on how to fix this problem and thought that using ErrorMiddleware (which is invoked in case of an error) should be the solution, but after some tests I saw that it is only invoked if a regular middleware invokes the next one by passing an error as the third argument or an uncaught exception is thrown. When a route is not matched (404) or it is matched with an incorrect HTTP method (405), the error middleware is not invoked.

After confirming (on Twitter) that this was the intended result he went about looking for another option. He looked into using "Final Handlers" that are called when nothing else matches in the middleware execution chain. They didn't provide one for JSON handling, however, so he had to create his own (code is included in the post) and explains a bit of how it's handling the data and HTTP response code. Unfortunately using this handler made the error output always return JSON so another piece was needed, the content-based detection handler that switches between types based on the Accept header.

tagged: content error handler zendexpressive tutorial json output

Link: http://blog.alejandrocelaya.com/2016/07/29/creating-a-content-based-error-handler-for-zend-expressive/

Loïc Faugeron:
Towards CQRS, Command Bus
May 12, 2016 @ 12:07:21

Loïc Faugeron has made a new post to his site talking about moving towards CQRS and Command Bus architecture in PHP applications.

By following the Command / Query Responsibility Segregation (CQRS) principle, we separate "write" logic from "read" logic. This can be applied on many levels, for example on the macro one we can have a single "Publisher" server (write) with many "Subscribers" servers (read), and on a micro level we can use this principle to keep our controllers small.

However, transitioning from a regular mindset to a CQRS one can be difficult. In this article, we'll explore the "Command Bus" pattern, to help us to get the Command (write) part right.

He starts with an example of a "create profile" happens and all logic lives in the controller. He then gets into the basics of the Command Bus handling and how the concept of "middleware" relates. He then shows how to migrate over to the Command Bus handling in his controller example, creating a CreateNewProfile command (with unit tests) and its handler. He then refactors the controller to put it to use. He points out that the initial version is tightly coupled to Doctrine so he refactors it too via some simple interfaces.

tagged: commandbus tutorial cqrs example refactor controller command handler

Link: https://gnugat.github.io/2016/05/11/towards-cqrs-command-bus.html

Matthew Weier O'Phinney:
Serve PSR-7 Middleware Via React
Apr 20, 2016 @ 12:07:56

Matthew Weier O'Phinney has a post to his site showing you how to combine PSR-7 request/response handling (his examples use Zend Expressive) with React and middleawre in your application.

I've been intending to play with React for some time, but, for one reason or another, kept putting it off. This past week, I carved some time finally to experiment with it, and, specifically, to determine if serving PSR-7 middleware was possible.

He starts with a brief introduction to React and what kind of functionality it brings to the table. He includes a bit of sample code showing it in use creating a basic HTTP server responding to any request with a simple "Hello World" message. He then starts on the React+PSR-7 integration, wrapping the request and response handling from one in the other to keep the expected responses the same. He also talks about serving up static files using the React+PSR-7 handling via a middleware on the Expressive side. Finally he shares the work he's done via a library to help make it easier to reuse in other situations. He shows the installation and usage of this library and sample requests you can use to test it out.

tagged: react psr7 request response example library handler static file tutorial

Link: https://mwop.net/blog/2016-04-17-react2psr7.html

Davey Shafik:
GuzzleHTTP VCR
Aug 24, 2015 @ 10:54:54

Davey Shafik has published a post about library he's created that's a sort of "recorder" for connections made with the Guzzle HTTP client - the Guzzle VCR.

A few days ago I pushed out a very small library to help with testing APIs using Guzzle: dshafik/guzzlehttp-vcr. [...] This is a simple middleware that records a request’s response the first time it’s made in a test, and then replays it in response to requests in subsequent runs.

The handler works by recording the responses from the API (ex: the JSON response data) and records them to files (again, JSON). A one-line call turns the "recording" on and points to a directory where the cached files should be stored. He shows how to use it in the constructor of your Guzzle client, setting it up as the "handler" for the requests. He also includes an example of a few unit tests that make use of the recording feature to check the response of a /test endpoint.

tagged: guzzle http client vcr recording response json cache handler

Link: http://daveyshafik.com/archives/69384-guzzlehttp-vcr.html

Philip Brown:
Dealing with Exceptions in a Laravel API application
Aug 10, 2015 @ 11:57:43

In a post to his site Philip Brown shows a helpful way to manage API exceptions in a Laravel-based API application. In an API, exceptions are particularly important as they can be a hint to what the problem is and make it easier to return the correct error code to the client.

Exceptions are a very important method for controlling the execution flow of an application. When an application request diverges from the happy path, it’s often important that you halt execution immediately and take another course of action.

In today’s tutorial I’m going to show you how I structure my Laravel API applications to use Exceptions. This structure will make it very easy to return detailed and descriptive error responses from your API, as well as make testing your code a lot easier.

He starts with a brief introduction to HTTP status codes and their role in the interaction between client and server. He then gets into the "exception foundation" and how it will work, providing some basic common functionality (like throwing a 404 when a record isn't found, regardless of the type). He creates a configuration file to define the default error messages, an abstract Exception the custom instances can extend. He creates several of these as an example, such as a "UserNotFound" exception that extends the base "NotFound" exception class. He works with Laravel's own exception handlers and includes the code to catch a few different types inside.

tagged: exception laravel api application custom base handler tutorial

Link: http://culttt.com/2015/08/10/dealing-with-exceptions-in-a-laravel-api-application/

Sameer Borate:
Debugging Laravel with MonoLog and FirePHP
Jun 07, 2013 @ 09:08:37

Sameer Borate has a new post to his site showing you how to debug a Laravel application with Monolog and FirePHP.

By default, Laravel is configured to create daily log files for your application, and are stored in app/storage/logs. All Laravel logging features are handled by the wonderful MonoLog library. Monolog includes various log handlers you can use – FirePHP, ChromePHP, CouchDB, Stream and many more. One of my favorites is FirePHP while debugging PHP apps.

Getting Monolog to write out to FirePHP is pretty easy and he includes the sample code to make it happen - basically pushing a "FirePHPHandler" into the Monolog instance and using it from there.

tagged: debug laravel monolog firephp handler tutorial

Link: http://www.codediesel.com/laravel/debuggin-laravel-with-monolog-and-firephp

PHPMaster.com:
Testing Error Conditions with PHPUnit
Oct 02, 2012 @ 11:57:40

Over on PHPMaster.com there's a new post for the unit testers in the audience (you all unit test, right?) from Matt Turland about testing error conditions in your applications.

Let’s say you’re maintaining code that uses PHP’s native trigger_error() function to log error information. Let’s also say that you’re in the process of using PHPUnit to write unit tests for that code. If you refer to the PHPUnit manual, there’s a section that deals with testing for error condition. [...] However, depending on what your code looks like, it’s possible that you’ll run into a problem with PHPUnit’s approach to this. This article will detail what this problem is, how it impacts your ability to test your code, and how to go about solving it.

He points out that, since errors and exceptions handle differently, you have to work with them differently in your tests. PHPUnit has a feature that automatically turns errors into a specific type of exception when they're thrown and how, by using a simple custom error handler, you can more correctly tests error vs exception.

tagged: unittest error exception phpunit tutorial handler custom

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Cory Fowler:
Enabling PHP 5.4 in Windows Azure Web Sites
Sep 21, 2012 @ 08:09:21

Cory Fowler has a recent post explaining how you can enable one of the most recent PHP releases (PHP 5.4) on your Windows Azure website via the " Bring-Your-Own-Runtime" feature.

Much like many other developers, I like to live on the bleeding edge, learning new language features, using the latest tools so naturally one of the things I wanted to see in Windows Azure Web Sites is support for PHP 5.4. I’m pleased to be telling you today in this post that support for Bring-Your-Own-Runtime is now available in Windows Azure Web Sites. Out of the box, Windows Azure Web Sites supports PHP 5.3 as you can see from the snapshot of the portal below. In this article I’ll explain how to enable PHP 5.4 in Windows Azure Web Sites.

You'll need to set up and configure an Azure instance to work with (if you don't already have one) and navigate to its management Dashboard once complete. You can then setup a handler mapping that points to an uploaded version of the PHP Windows binary for 5.4 on your document root. Then all that's left is to upload (via FTP or git) this executable and you'll be all set.

tagged: windows azure version tutorial handler exe

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PHPMaster.com:
Amazon DynamoDB: Store PHP Sessions with Load Balancer
Sep 13, 2012 @ 11:19:57

PHPMaster.com has a new tutorial posted showing how you can work with the Amazon DynamoDB to store session information from your PHP application (originally posted on CloudSpring).

This tutorial will show you how to use Amazon DynamoDB as a storage facility for PHP sessions. This method becomes very useful when your applications take advantage of the Elastic Load Balancing and Autoscaling services. You will need Amazon AWS account enabled to use EC2, Elastic Load Balancer and DynamoDB as a prerequisite to play along the tutorial.

He starts with a description of what the elastic load balancing service is and how it autoscales. He shows how, based on this demo application, to use a custom PHP session handler that implements the Amazon SDK libraries to hook into the DynamoDB service. Also included are screenshots (and the steps that go with them) to configure the service itself.

tagged: amazon dynamodb session handler tutorial custom

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Justin Carmony's Blog:
PHP, Sessions, __sleep, and Exceptions
Mar 27, 2012 @ 12:25:02

Justin Carmony has a recent post to his blog about a problem he came across where his exception was being thrown with a line number of zero - cause for some investigation.

Today I ran into a problem where my PHP Application would throw this fatal error: "Fatal error: Exception thrown without a stack frame in Unknown on line 0". Which is so much fun, because it doesn’t have a line number, so I had no direction as to what exactly was causing the problem.

He found a blog post that helped him track down the issue that, as it turns out, with serializing objects into the session and an error in the __sleep method.

tagged: exception problem sleep serialization error handler

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